The present invention relates generally to line testing in a telephony system, and in particular to intelligent and automated line testing.
Subscribers to the public switched telephone network (PSTN) are typically connected to a local switching system via groups of wires, commonly referred to as subscriber lines or subscriber loops. Telephone companies serving these subscribers must test these lines for operability and quality. Such testing may occur when known problems exist, or during preventative maintenance to monitor line quality or detect outages. Given the ever-increasing number of subscribers and lines necessary to service these subscribers, significant time and resources are dedicated to providing routine, automated line testing (ALT) for the subscriber lines.
Traditionally, automated line testing was conducted, by instructing a switch to sequentially test a range of numbers associated with a group of subscriber lines handled by the particular switch. As shown in FIG. 1, an operational support system (OSS) 10 is used to decide which subscriber lines to test. Testing occurs when the OSS 10 sends instructions to one of the test heads 12 to test a group of subscriber lines 14 handled by switch 16. As depicted, the subscriber lines 14 connect a line interface 18 with a subscriber 20. Exemplary line testing capable OSS""s are Nortel Networks"" AccessCare, Lucent Technologies"" LMOS-MLT, and Teradyne""s 4TEL.
The test heads 12 connect to a metallic test access cross-connect (MTACC) 22 over dedicated analog test trunks or pairs 24. The MTACC 22 may selectively connect any one of the analog test trunks directly to a line interface 18 associated with a subscriber line 14. Notably, the connection between the test head 12 and a selected subscriber line 14 is a direct, metallic connection. Preferably, the test heads 12 are fairly proximate to the switch 16, and the metallic connection between the test head 12 and the tested subscriber line 14 is as direct as possible.
To test any particular subscriber line 14, the OSS 10 sends an appropriate instruction to a test head 12. The test head will dial a number associated with the subscriber line 14 over the analog test pairs 24. The switch 16 recognizes that the number dialed over the analog test trunk is an instruction to facilitate a line test for the associated subscriber line 14. The switch 16 then effects a direct connection between the analog test pairs 24 and the line interface 18 associated with the subscriber line to be tested. At this point, the test head 12 has a direct, electrical and mechanical connection to the tested subscriber line 14 and tests the subscriber line 14 in traditional fashion. For automated line testing, the OSS 10 will instruct a test head 12 to test subscriber lines associated with a range of numbers. For example, the OSS 10 may instruct the test head 12 to test all subscriber lines 14 having a local exchange 555-XXXX. As such, all numbers within the exchange from 555-0000 through 555-9999 are tested.
Unfortunately, the OSS 10 has little or no information regarding the actual hardware configuration of the switch or how the various subscriber lines are arranged and placed within the numerous shelves, drawers, and cards used to store the line interfaces 18. Further, there are typically at least two test heads for any given switch 16, and the test heads 12 typically test their set of lines concurrently. Since there is no coordination between the OSS 10 and the allocation and assignment of subscriber lines 14 in the switch 16, there is often contention for common resources between the test heads 12 during automated line testing.
Typically, the test head 12 can only test one subscriber line at a time. Further, the switches 16 are normally configured such that the MTACC 22 can provide only one access path for any group of subscriber lines 14. For example, the MTACC 22 may only provide one connection for a shelf of line interfaces 18. Thus, only one test head 12 can gain access to the shelf at any given time. Since the OSS 10 doesn""t know the assignment and allocation of the subscriber lines 14, it may request multiple test heads 12 to simultaneously test subscriber lines 14 that are on a common shelf. When this happens, there is a contention for access to the subscriber lines 14 by the test heads 12. As such, there is an interruption in the automated line testing for one of the test heads 12.
Another type of interference with line testing occurs when a subscriber 20 is using the particular subscriber line 14 slated for testing. The automated line testing is interrupted, because the OSS 10 isn""t aware that the subscriber line 14 is being used. For smaller switches 16, contention between test heads 12 and use by subscribers 20 have not posed significant barriers to line testing. Larger switches and media gateways providing switching functions are more greatly affected by decreases in line testing efficiency. For example, the smaller switches may support only 640 lines or less. In contrast, larger gateways may support up to 16,000 lines or more and may be further grouped in clusters where millions of lines require testing on an automatic and periodic basis. As such, there is a need for an efficient and intelligent way to provide automated line testing in an efficient manner that avoids the contention or line use problems described above.
The present invention provides for intelligent and efficient line testing by allowing a test control entity, such as an operational support system (OSS), to obtain information bearing on testing telephony lines. The information to be obtained relates to the structure or operation of the switching device. Preferably, the information obtained includes suggestions of which lines to test using test heads associated with the switching device. The suggestions may include a list of numbers that can be tested concurrently. Such suggestions may assist the OSS in providing instructions to the test heads to avoid line contention during testing, testing lines that are in use, or any number of scenarios potentially detrimental to efficient line testing. The information or suggestions may be obtained from an element manager or like entity having information about a particular switching device, or may be obtained directly from the switching device.
As such, the OSS will request line test instructions from the element manager or gateway, which will in turn provide line test instructions or suggestions back to the OSS. Based on the received information, the OSS will develop and provide line instructions to one or more test heads, which will carry out line tests at the switching device.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon reviewing the following description of the preferred embodiments of the invention in conjunction with the accompanying figures.